1. Field of the Invention
The present invention pertains to an imaging device and imaging method that divide a two-dimentional photo object, such as a document or photo, into multiple parts, take their images, and splice the obtained image data of the sections to obtain a high-resolution complete image.
2. Description of the Related Art
As an imaging device that divides the photo object into multiple parts, take their images, and splices the image data of the sections to obtain a complete image, the following devices are conventionally known.
One such device is a device that has two mirrors in the light path between the area sensor and the photo object, and the photo object image is divided into multiple parts and projected onto the area sensor by rotating these mirrors in the X and Y directions, respectively (see Japanese Laid-Open Patent Application Hei 8-265628).
Another such device moves the area sensor relative to the complete photo object image projected by means of the optical system and reads the photo object image by dividing it into multiple parts (see Japanese Laid-Open Patent Application Hei 7-107379).
Where the mirrors are rotated as in the former example, the mirrors are located such that they are angled relative to the optical axis of the imaging optical system, and the photo object image is sequentially projected onto the area sensor while the angles of the mirrors are caused to change from time to time. Consequently, mirrors having a large surface area are needed. In addition, since space in which the mirrors may be rotated is needed, the entire imaging device becomes large in size. Furthermore, as the mirrors rotate, the photo object becomes no longer parallel to the imaging element, resulting in the so-called tilt state. As a result, blur and distortion occur in the image formed on the imaging element. Further, because the photo object is moved in a two-dimensional fashion, the two mirrors must be individually rotated, which futher contributes to increasing the size of the entire imaging device, as well as to increased image blur and distortion.
Where the area sensor is moved as in the latter example, the area sensor must be moved within the same plane, but in actuality it is difficult to completely eliminate rattling of the drive mechanism due to gear backlash, etc. Therefore, the area sensor does not move within the same plane in a parallel fashion, due to the rattling of the drive mechanism. In other words, the area sensor rotates slightly around the optical axis of the imaging optical system, and thus the obtained images of sections of the photo object or partial images are rotated relative to the images of other sections. If the partial images are rotated relative to each other, when two or more of them are spliced together, the image data positions must be corrected, but detection of the amount of rotation of the area sensor or the images, as well as correction of the image data, is very complex and difficult. Therefore, using these conventional constructions, the problems arise that the entire imaging device increases in size and cost, and that the processing required for the splicing of partial images becomes complex.